Clean rooms of this type, to which the present invention relates in particular, are used predominantly in the fields of pharmaceutics, biotechnology and microelectronics. Operations or production processes must be performed in clean rooms in closed spaces under controlled conditions. Depending on the application and requirements related thereto, various parameters such as, e.g., air temperature, air humidity, room pressure, particle and germ count can be influenced or controlled in a targeted manner in such clean rooms. Depending on the required degree of purity, excess pressure or negative pressure in the clean room, different clean room classes have been known and standardized.
In order to maintain one or several of the aforementioned parameters in a clean room, special ventilation systems are used. Despite occurring disturbances such as, e.g., thermal, humidity and substance loads, said ventilation systems must ensure that prespecified parameter values be maintained.
In practical settings, ventilation systems for clean rooms have been known in various configurations. Generally, these are systems with several functional units that, e.g., are installed in an intermediate ceiling area above a clean room, e.g., on walkable clean room ceiling, and are connected to each in accordance with flow technology. In most cases, there is a fan-and-filter unit that comprises a ventilation device and, e.g., a particulate air filter in order to introduce clean air through a supply duct into the clean room. The clean air is introduced in the room at a relatively high flow rate in order to allow a very high air exchange as needed. Some systems allow an air exchange of up to 400 times per hour, thus requiring appropriately high flow rates. With the use of another unit that also may comprise an air filter, used waste air is removed from the clean room. In most cases, this waste air removal unit is fluidically connected to an air processor that suitably conditions the exhaust air and mixes it, in particular, with fresh outside air in order to provide conditioned, clean air for the fan-and-filter unit. Furthermore, a cooler or heater for the thermal treatment of the ingoing air to be supplied to the clean room may be provided.
All of these functional units are connected to each other by means of a branched duct network that conveys the individual air flows. The volume flows are regulated with the aid of control valves arranged distributed in the duct system and by control of the ventilating devices, ensuring the air transport. To accomplish this, a controller that is separate from and imposed on the functional units is provided, said controller monitoring and regulating the prespecified parameters in the clean room such as temperature, pressure, etc., with the aid of associate sensors and a logic control.
The design of such a ventilation system is complex in that it requires considerable space for the different functional units, the duct network, the sensors and the control system. In addition, the expenses for installation and startup are relatively high due to the numerous connections between connectors that need to be provided, the relatively complex preliminary wiring and preliminary specification of parameters. Also, the maintenance and servicing of such a distributed system is difficult. During operation, problems can occur when adapting the functional units to each other and when regulating them.
Also, so-called “fan-filter units” have been known, these forming a combined unit of a fan and a particulate air filter as well as, potentially, a cooler that can be installed in the ceiling of a room. Such circulated air devices simplify the design of a ventilation system to the extent that they ensure the introduction of ingoing air into the room as well as the removal of the waste air by using a single circulated air device. The supply of outside air, however, occurs in a separate air conditioner that is fluidically connected to the circulated air device. Furthermore, the volume flow controllers and their associate intelligent features for control, monitoring and energizing are arranged outside the circulated air device, this potentially being related to the aforementioned inadequacies or disadvantages.
There is the desire of further combining the different functional units in order to create highly compact, integrated ventilation devices that are able to reduce the expenses for installation, startup and maintenance. However, due to the different applications, specifications and required degrees of purity, different clean rooms pose different requirements for supplying and extracting air. Furthermore, changing production processes and clean room equipment may also pose different requirements for air supply and air extraction. To this extent, it appears difficult to provide a universal compact device for the supply and extraction of air in clean rooms, whereby said device would be able to satisfy such varied requirements.